This invention generally relates to a temperature-based sensor for detecting undesirable vibrations or temperatures in a vehicle component.
Due to driving conditions and vehicle operation, many of the components undergo vibrations, which cause the components to deviate from the desired direction of movement. Further, many vehicle components must be maintained within particular temperature ranges to assure proper performance. It is therefore necessary to monitor the vehicle components to assure that they are operating in the proper temperature and vibration ranges to prevent undesirably worn or damaged components.
In order to monitor the temperature and vibration characteristics of the vehicle components, a power source is needed. This power supply must be available at all times during the operational life of the vehicle. This operational time period could be greater than ten (10) years. To provide a ready power source for this length of time is very expensive.
Thus, it is desirable to have a temperature and vibration sensing system that can be powered efficiently and economically throughout the operational life of the vehicle. The system should also be easy to install and maintain.
In a disclosed embodiment of this invention, a sensor system is used to determine the temperature of a vehicle component. The system includes a housing and a thermally sensitive sensor assembly for generating a signal responsive to the sensor detecting a temperature in the vehicle component that exceeds a predetermined temperature. A power supply is supported by the housing and is used to generate electricity to power the sensor assembly. The power supply is inactive until a predetermined condition is achieved. Preferably, the power supply becomes operational when the temperature of the vehicle component achieves an initial threshold temperature that is less than the predetermined temperature.
In one disclosed embodiment, the power supply is fixed to the housing during operational temperatures that are less than the initial threshold temperature so that there is no relative motion between the power supply and the housing. The power supply is moveable relative to the housing once operational temperatures exceed the initial threshold temperature. Preferably, the power supply is attached to the housing by a material having a melting temperature that is approximately equal to the initial threshold temperature. When the subject vehicle component reaches the initial threshold temperature, the material melts away allowing a portion of the power supply to move relative to the housing.
In one preferred embodiment, the power supply includes a rotating component and a stationary component that is fixed for movement with the housing. When the material melts, the rotating component is allowed to rotate with respect to the stationary component. Preferably, the rotating component is a magnet and the stationary component is a coil assembly such that as the magnet rotates with respect to the coil, electricity is generated to supply power to the sensor system.
The preferred method, for determining temperature of a vehicle component includes the following steps. A sensor assembly is mounted to a vehicle component. A power supply is activated to power the sensor assembly when the component operating temperature exceeds an initial threshold temperature. A signal is generated in response to the sensor assembly detecting a temperature in the vehicle component that exceeds a predetermined temperature that is greater than the initial threshold temperature.
These and other features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description.